//  THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
//  KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
//  IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
//  PURPOSE.
//
//  This material may not be duplicated in whole or in part, except for 
//  personal use, without the express written consent of the author. 
//
//  Email:  ianier@hotmail.com
//
//  Copyright (C) 1999-2003 Ianier Munoz. All Rights Reserved.

using System;
using System.IO;

namespace WaveLib
{
    public class WaveStream : Stream, IDisposable
    {
        private Stream m_Stream;
        private long m_DataPos;
        private long m_Length;

        private WaveFormat m_Format;

        public WaveFormat Format
        {
            get { return m_Format; }
        }

        private string ReadChunk(BinaryReader reader)
        {
            byte[] ch = new byte[4];
            reader.Read(ch, 0, ch.Length);
            return System.Text.Encoding.ASCII.GetString(ch);
        }

        private void ReadHeader()
        {
            BinaryReader Reader = new BinaryReader(m_Stream);
            if (ReadChunk(Reader) != "RIFF")
                throw new Exception("Invalid file format");

            Reader.ReadInt32(); // File length minus first 8 bytes of RIFF description, we don't use it

            if (ReadChunk(Reader) != "WAVE")
                throw new Exception("Invalid file format");

            if (ReadChunk(Reader) != "fmt ")
                throw new Exception("Invalid file format");

            int FormatLength = Reader.ReadInt32();
            if (FormatLength < 16) // bad format chunk length
                throw new Exception("Invalid file format");

            m_Format = new WaveFormat(22050, 16, 2); // initialize to any format
            m_Format.wFormatTag = Reader.ReadInt16();
            m_Format.nChannels = Reader.ReadInt16();
            m_Format.nSamplesPerSec = Reader.ReadInt32();
            m_Format.nAvgBytesPerSec = Reader.ReadInt32();
            m_Format.nBlockAlign = Reader.ReadInt16();
            m_Format.wBitsPerSample = Reader.ReadInt16();
            if (FormatLength > 16)
            {
                m_Stream.Position += (FormatLength - 16);
            }
            // assume the data chunk is aligned
            while (m_Stream.Position < m_Stream.Length && ReadChunk(Reader) != "data")
                ;

            if (m_Stream.Position >= m_Stream.Length)
                throw new Exception("Invalid file format");

            m_Length = Reader.ReadInt32();
            m_DataPos = m_Stream.Position;

            Position = 0;
        }

        public WaveStream(string fileName) : this(new FileStream(fileName, FileMode.Open))
        {
        }
        public WaveStream(Stream S)
        {
            m_Stream = S;
            ReadHeader();
        }
        ~WaveStream()
        {
            Dispose();
        }
        new public void Dispose()
        {
            if (m_Stream != null)
                m_Stream.Close();
            GC.SuppressFinalize(this);
        }

        public override bool CanRead
        {
            get { return true; }
        }
        public override bool CanSeek
        {
            get { return true; }
        }
        public override bool CanWrite
        {
            get { return false; }
        }
        public override long Length
        {
            get { return m_Length; }
        }
        public override long Position
        {
            get { return m_Stream.Position - m_DataPos; }
            set { Seek(value, SeekOrigin.Begin); }
        }
        public override void Close()
        {
            Dispose();
        }
        public override void Flush()
        {
        }
        public override void SetLength(long len)
        {
            throw new InvalidOperationException();
        }
        public override long Seek(long pos, SeekOrigin o)
        {
            switch (o)
            {
                case SeekOrigin.Begin:
                    m_Stream.Position = pos + m_DataPos;
                    break;
                case SeekOrigin.Current:
                    m_Stream.Seek(pos, SeekOrigin.Current);
                    break;
                case SeekOrigin.End:
                    m_Stream.Position = m_DataPos + m_Length - pos;
                    break;
            }
            return this.Position;
        }
        public override int Read(byte[] buf, int ofs, int count)
        {
            int toread = (int)Math.Min(count, m_Length - Position);
            return m_Stream.Read(buf, ofs, toread);
        }
        public override void Write(byte[] buf, int ofs, int count)
        {
            throw new InvalidOperationException();
        }
    }
}
